There are known many types of gauging, or measuring, heads for the inspection of mechanical pieces in benches, transfer lines or in the course of the machining in machine tools in applications of the so-called “in-process” type.
Even though the known heads ensure good performance insofar as the repeatability and the reliability are concerned, they are generally dedicated to specific types of applications and do not allow a broad flexibility of use.
In other circumstances, even though the heads would be suitable for a number of applications, they require lengthy, expensive and toilsome retooling operations.
The transducer devices of the known heads, for example of the linear voltage differential transformer, or half-bridge type, with reciprocally movable windings and core have a linear performance in an extremely limited area of displacement between the core and the windings, hence permitting limited measuring ranges. Moreover, these transducer devices have a structure that is delicate and particularly sensitive to temperature variations that cause undesired drifts, known as “thermal drifts”, in the course of the operation of the heads.
The known heads also include cables with electric wires that enable the sending of signals from the associated transducers to the processing units, and connectors at the free end of the cables. The connectors of the known heads have elements intended to be coupled to each other, for example, by means of a threaded coupling, that requires particular care on behalf of the operator for achieving the appropriate locking and sealing.
There are also known apparatuses comprising frames for supporting these heads, for example, supports for supporting and referring a pair of heads in applications for the diameter checking. The heads can be coupled to the support in an adjustable way, both reciprocally and with respect to the support. Apparatuses of this type are utilized, for example, for the diameter checking of pieces in the course of the machining in machine tools, more specifically, in grinding machines. The component parts of the apparatus, more specifically the gauging heads, can be subject to accidental and undesirable collisions, frequently occurring especially in the workshop environment where there are applications of the “in-process” type. These collisions can alter the checking position of the heads, besides cause damage to the actual heads.